psfxtable

psfxtable [-h]

-h
    Display help message.

The `psfxtable` command is a utility for displaying detailed information about shared memory segments in a Linux system. It primarily focuses on segments created or accessed by programs using System V shared memory functions (shmget, shmat, shmdt, shmctl). The command displays details like the shared memory ID, key, owner, permissions, size in bytes, number of attached processes, and the last attach/detach times. It often requires root privileges or appropriate permissions to access all shared memory regions. The tool is useful for debugging shared memory related issues, monitoring shared memory usage, and identifying potential memory leaks or misconfigurations in applications using shared memory for inter-process communication (IPC). This tool is most useful for system administrators or developers debugging IPC problems.

Unlike `ipcs`, `psfxtable` typically provides more detailed timestamps and potentially more process context if the supporting infrastructure is present. It relies on the `proc` filesystem and system calls to gather information about shared memory segments and the processes using them.

Requires root privileges to view all shared memory segments. The output may vary depending on the kernel version and system configuration. This command may not be present on all Linux distributions or may be part of a larger package.

The output typically includes fields such as:
shmid: Shared Memory ID
key: The shared memory key.
owner: The user and group ownership.
perms: Permissions associated to the shared memory
bytes: The size of the shared memory segment in bytes.
attached: The number of processes attached to the shared memory segment.
last_attach: Timestamp of the last attach operation.
last_detach: Timestamp of the last detach operation.

ipcs(1), shmget(2), shmat(2), shmdt(2), shmctl(2)